Bugfix on 1.2.0: fix binding's tests

I'd forgotten to update the ad-hoc tests for binding to correspond to reality. This is otherwise the same as 1.2.0.

A rollup of several improvements

Since the last release:

• collecting has, finally, become a shim for with-collectors which was long overdue;
• there are general accumulators by with-accumulators, which are quite powerful;
• binding has bind/macro for macrolet;
• local functions and macros bound by binding themselves implicitly use binding;
• bind/values will ignore nil allowing you to skip some values;
• there is a new hack, stringtable which is a simple readtable for strings;
• there are some other improvements which shouldn't involve new or repaired functionality.

The documentation should correspond to what exists: in particular all of the new things above are described.

Add binding forms, make macro tracing more robust

binding is a new hack which allows things like

(binding
  ...
  (bind x 1)
  (bind y 2)
  ...
  (bind (f a b)
    (+ a b))
  (f x y))

These get expanded into code which uses let* &c.

trace-macro is also a bit more robust against possible bad tracing states (for instance if it thinks it should be tracing but there's no wrapped hook it will offer ways to recover). None of these should ever happen in practice.

Initial public version

v1.0.0

v1.0.0